What’s in the Sky
September 2020

With September, we come to my favorite month for stargazing.  Darkness comes earlier, yet nights are still warm.  Weather is usually good, particularly in early September.  And this year, there is plenty to see in the night sky.

Bright planets continue to dominate in the southern sky, with Jupiter and Saturn prominent to the left of the Milky Way.  Venus still shines bright in the morning sky.


Now watch for Mars – the planet rises by about 9:30pm at the start of the month, and by about 7:30pm at the end of September.  Mars will be brighter than Saturn, but not quite as bright as Jupiter.  And it will be noticeably reddish in color.  The Red planet will be about 46 million miles from us at the start of the month, closing to about 39 million miles distant at month’s end.

Our Moon will be full on September 2, with new Moon following on the 17th.  A nice sight in early September will be on the 5th, when Mars will appear very close the Moon, only a couple of Moon-diameters away.  On the 9th, the waning Moon will lie below the Pleiades star cluster.  On the 18th, the thin crescent of the new Moon will lie just above the planet Mercury, low on the western horizon at sunset.  If you have a good view of the western horizon, see if you can spot them both after sunset.  On the 24th, the Moon will lie just below Jupiter in the southern sky.

September 22 marks the Autumnal Equinox, the first day of fall.  At that time, the length of day and night is approximately equal, hence the name.  On the equinox, the Sun lies directly over the equator.  On that date, the Sun rises due east, and sets due west.  And it is true, you can balance an egg on its end on the equinox!  Of course, you can balance an egg on its end any day, with a little practice.

This month’s binocular object is another galaxy, an entire system of stars, larger than our Milky Way galaxy, located some 2.5 million light-years from us.  We can see the cumulative light from its billions of stars as a soft glow, in the constellation Andromeda.  It carries the constellation’s name, the Andromeda galaxy.  The galaxy is barely visible to the naked eye, as I’ve mentioned before in this column.  It is quite noticeable in a pair of binoculars, though.  So, where to look?  It will be located in the eastern sky on September evenings.  Look east, and look for 4 almost equally bright stars making up a large “square” in the sky.  The “square” is tilted, with one “corner” star up, one lower in the sky, one farther to the south, and one farther to the north.  Check out the picture with this article for help finding it.  That “square” is in the constellation Pegasus, and is referred to as the great square in Pegasus.  The star in the square that is farthest north is Alpheratz.  Look to the left of Alpheratz, and find a couple of lines of 3 moderately bright stars each.  The lower line consists of brighter stars, with the middle star being the brightest.  That star is Mirach.  Look just above Mirach to see the middle star in the upper line, one not as bright as Mirach.  That star is Mu Andromedae.  Now look just above Mu, about as far above it as it is above Mirach.  Point your binoculars toward that area, and you should pick up the faint flow of the galaxy.  Use the picture with this column to locate it.

Enjoy September’s night skies!